Water in Hams/Finding Equilibrium

Efforts to manage the humidity in the fridge where the prosciutto and molasses ham are stored continue with limited success. Take a look at the chart below.

Temp/Humidity Chart

The temperature, shown as a blue line above, has consistently maintained about 60° F (15.5°C). Over the past couple of weeks the humidity has also been fairly steady, ranging between 55% and 63% until it suddenly jumped to about 86.7% on July 26th.

So, what happened? Because the humidity was still a little low, I tried adding more water to the saltwater solution in the fridge. The water activity of the prosciutto at a one inch depth had been down to 0.859aw. This week, after the humidity hike, moisture was beading on the exterior of the hams and the prosciutto tested at 0.862aw – slightly higher than the previous week. Moisture migrates from high water activity to low, so moisture from the air migrated into the ham.

The molasses ham, however, continued to decrease because the water activity of the ham was still above 0.91, even higher than the humidity in the fridge.

Now the humidity seems to be leveling off at about 74% – right where we want it. Let’s see if we can maintain it.